A parking assistance system, which is a system for helping a driver to more easily and conveniently park a vehicle, recognizes a parking space through a sensor mounted in a vehicle, calculates an optimum path, through which the vehicle may be parked within the recognized parking space, and automatically controls a steering wheel or assists driver's operation of a steering wheel by an audio-visual method.
As one example of the parking assistance system, a parking assistance system based on an ultrasonic wave sensor appears, and the parking assistance system based on the ultrasonic wave sensor recognizes a surrounding obstacle and a parking space through the ultrasonic wave sensor and generates a movement path of a vehicle. However, in the case where an obstacle is not present, there is a disadvantage in that it is difficult for the parking assistance system based on the ultrasonic wave sensor to recognize a parking space, and the parking assistance system based on the ultrasonic wave sensor is influenced by an obstacle disposition state around the parking space (for example, in the case where a next vehicle is parked to be misaligned to a parking line), and thus a parking assistance system based on a camera image has been recently considered.
However, even though the parking assistance system is based on any one of the ultrasonic wave sensor, the camera, and the like, in order to have an effective detection range and recognize an accurate parking space, a vehicle needs to be disposed at an appropriate position in a parking space and the like. That is, when the system is operated at a position which is spaced apart too far from a parking line or a parking space, the system gets out of the effective detection range or has degraded detection accuracy, so that it is difficult to reliably recognize a parking space and guide the parking. The aforementioned problem causes inconvenience in that the system is not operated or recognition performance deteriorates even though a user, who is not accustomed to use the parking assistance system, approaches close to a parking line.